A US operator was planning to drill a closed-loop geothermal land well with an estimated bottom hole static temperature of 400°C. Operating in such extreme heat could lead to risk of equipment failure, so it required an efficient and reliable method to ‘stage’ in the hole to cool down the temperature sensitive measurement while drilling (MWD) technology and other directional tools.
Staging is a common practice for high temperature wellbores to prevent MWD failures which normally involves pumping conventionally though the drill bit to cool the BHA. However, as this method can result in the motor rotating the drill bit, and causing possible damage in the cased and upper granite section as well as damage to the drill bit teeth, a more reliable method was required.
The application of the DAV MX delivered significant time savings while maintaining well integrity and improving safety. Estimated bottom hole temperatures were reduced from an estimated 400°C to 210°C whilst drilling using the circulation sub.
Coretrax’s DAV MX downhole circulation tool can be used across a wide range of applications including hole cleaning, displacements, lost circulation material spotting, blowout preventer jetting and many others. The rapid, smart dart’s activation speed, versatility and robustness gives the operator fast circulating options in nearly any circumstance.
The tool was deployed with the Split Flow Dart which allowed a limited flow through the motor and drill bit, reducing the rotations per minute whilst delivering high flow rate to effectively cool the BHA and borehole.
“The geothermal market has experienced significant growth in recent years in response to global environmental objectives and Coretrax already has a tangible track record in supporting these developments globally” said John Fraser, chief executive officer at Coretrax. “Our range of downhole circulation tools are ideally placed to support the high temperatures and complexities of geothermal wells. This latest project is a strong example of how technology which has traditionally been applied to oil and gas operations can support this expanding sector to address the most complex well challenges while delivering enhanced reliability and greater efficiencies.”
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